1. Field of the Invention
This invention relates to a casing for housing a disc cartridge for containing a disc-shaped recording medium therein. More particularly, it relates to a disc cartridge casing for housing a plurality of disc cartridges.
2. Background of the Invention
There has hitherto been presented a variety of disk-shaped recording media, referred to hereinafter as discs, enabling recording of information signals. During transportation or non-using period, the discs are stored in a sturdy casing. A compact disc, for example, having a larger thickness, is directly contained in a casing made up of a casing main member and a lid rotatably mounted on the casing main member, because there is no necessity to take protective measures against dust and dirt deposition (see for example U.S. Pat. Nos. 4,874,085 and 4,535,888).
The casing for the compact disc includes a holding protrusion at a mid portion of the major surface of the casing main member which is slightly larger than a center opening in the compact disc and which may be resiliently flexed towards the center by providing plural radially extending grooves, and a recess of a diameter substantially equal to the outer diameter of the compact disc surrounding the holding protrusion. The lid is in the shape of a saucer of a shallow depth and is provided with a plurality of holding lugs facing its peripheral wall. A printed matter, such as a song word card, is inserted between the holding lug and the inner surface of the lid.
Thus the compact disc is contained and held within the casing by having the holding protrusion engaged in the center aperture of the disc and by having the disc rim kept in pressure contact with the inner peripheral wall of the recess.
A small-sized magnetic disk, employed in an information or office equipment, has a magnetic material coated on its film-like sheet, so that it is contained in a disk cartridge for protecting its information signal recording surface. Such magnetic disk cartridge is contained in a casing made up of a casing main body 2 and a lid 3, as shown in FIG. 1.
The casing main body 2, formed of plastics, is plate-shaped on the whole, and has a channel-shaped holding section 5 forming a pocket 4 towards an edge of one of its major surfaces, and a pair of through-holes 6 on both lateral sides of the holding section 5 which are aligned axially with each other.
The lid 3, molded from transparent plastics, is formed as a square saucer of shallow depth, having one of the lateral sides removed, and is formed with dowels 8 on the inner surfaces of both lateral sidewall sections towards the open side. The dowels 8 are formed in register with the through-holes 6 in the casing main body 2 and are axially aligned with each other.
In assembling the casing 1, the lid 3 is connected to the casing main body 2, as the lateral sides of the lid 3 are extended apart so that the dowels are engaged in the through-holes 6. As a result thereof, the lid 3 is pivotally mounted on the casing main body 2. The magnetic disk cartridge 9 may be housed within the casing 1 by having its lateral side introduced into the pocket 4.
As for the magneto-optical disc, a laser light beam is radiated on the signal recording layer for heating it, and an external magnetic field is applied to the recording layer for recording desired information signals in a direction of magnetization corresponding to the direction of the external magnetic field. Since the laser beam is employed for recording and reproducing information signals in the magneto-optical disc, the information signals may be recorded and/or reproduced with an extremely high density. For example, music signals continuing for approximately 70 minutes may be recorded on the magneto-optical disc having a diameter of 12 cm.
The magneto-optical disc, which permits high density recording and/or reproduction of information signals, is deteriorated in recording/reproducing characteristics, even if only a small amount of dust and dirt is deposited on its signal recording surface. Consequently, the magneto-optical disc is contained in a disc cartridge, similarly to the above-mentioned magnetic disk (see for example U.S. Pat. No. 4,807,079).
In order for the magneto-optical disc to be positively integrated to a disc table of a disc drive apparatus with high precision positioning with respect to the center of rotation of the disc table, a magnetic metal plate is mounted at the center opening of the disc (see for example U.S. Pat. No. 4,829,510). Consequently, the optical disc cartridge having a magneto-optical disc contained therein cannot be contained in a casing adapted for holding the disc by taking advantage of the center aperture of the disc, as in the case of the above-mentioned compact disc, in view of the reduced thickness and flexibility of the magneto-optical disc. For this reason, a casing made up of a casing main body having a container pocket and a pivotally mounted lid, similarly to that used for a floppy disk, is generally employed.
Although it is possible with an optical disc having the diameter of 12 cm to record information signals continuing for approximately 70 minutes, a classic music, continuing for an extended period of time, cannot be recorded in one optical disc, so that it is recorded in plural discs. Besides, there may be occasions wherein an album is to be edited by plural optical discs.
If a work is to be recorded on a plurality of optical disc cartridges, these optical disc cartridges are naturally contained in one and the same casing.
If plural optical disc cartridges are to be contained in the above-described conventional casing, it may be contemplated to increase the pocket size in proportion to the number of the optical disc cartridges to be contained in the casing.
However, with the above-described casing for the optical disc cartridges, it is naturally difficult to form plural partitions within the pocket. Thus the optical disc cartridges are inserted loosely in the pocket. The result is that it becomes necessary to take out the optical disc cartridges out of the casing as the correct sequence of the optical disc cartridges contained in the casing is confirmed each time the disc cartridge is to be used, thus rendering the cartridge takeout operation labor-consuming.
It is also difficult to set aside a space for the printed matters, such as exposition of the numbers or the song word cards, within the casing. Besides, it is difficult to accommodate the exposition or the song word card in the casing so as to be associated with the correct optical disc cartridge.
In other words, if, when a work is to be constituted by plural optical disc cartridges, the conventional casing is to be remodelled for accommodating plural optical disc cartridges, the casing thus remodelled is simply a casing for accommodating several optical disc cartridges or several song word cards. Consequently, the casing is not in orderly state as a commercial product, while it cannot be put to practical use conveniently.
On the other hand, if the music recorded in the optical disc cartridge is to be played outdoors, it is necessary to transport several optical disc cartridges. Since the conventional practice is to have an optical disc cartridge contained in one casing, several casings need to be transported, which means a cumbersome operation.